Control valve apparatus



Dec; 28, 1948. m u ETAL CONTROL VALVE APPARATUS 2 Sheets-Sheet 1 Filed May 24, 1946 BRAKE VALVE BRAKE CYLINDER ATTORNEY D 9 v G. T. M cLuRE ETAL 2,457,534

CONTROL VALVE APPARATUS Filed May 24, 1946 I 2 sheets-Shea. 2

INVENTOR. GLENN T. McCLURE BY JOHN W. RUSH AT TORN EY Patented Dec. 28, 1948 UNITED STATES PATENTY OFFICE.

Glenn '1. McClure,

'Rush, Wilkinsburg, inghouse Air Brake McKeesport, and John W. Pa., assignors to The West- Company, Wilmerding, Pa.,

a corporation of Pennsylvania Application May 24, 1946, 'Serial No. 672,134

(o1. cos-69 7 Claims.

This invention relates to control valve app ratus and has particular relation to control valve devices of the type adapted especially for use in fluid pressure brake .control systems on railway cars and trains for controlling the release of fluid under pressure from the brake cylinder and the subsequent resupply of fluid under pressure to the brakecylinder upon the occurrence of a slipping condition of the wheels for the purpose of preventing the sliding of the car wheels.

Various types of control. valve devices have been heretofore employed for effecting the release of fluid under pressure from a brake cylinder and the subsequent resupply of" fluid under pressure to the brake cylinder in response to the occurrence of a slipping condition of, the car Wheels induced by an excessive degree of brake application. One type of such controlvalve device is disclosed and claimed in the prior copending application of Joseph.C.. McCune, now Patent 2,417,209, issued March, 11, 1947, and assigned to the assignee of this application In the type of control valve device disclosed in the aforesaid patent, a pneumatic connection in the form of a flexible conduit or pipe is provided between the control valve device and a socalled Decelostat pilot valve carried in a'casing attached to the outer end of the journal of a wheel axle whereby the control valve device is operatively controlled in response to the operation of the Decelostat pilot valve whenever a slipping condition of the vehicle wheeloccurs.

The control valve device is automaticallyopera ted in response to the operation of the Decelostat pilot valve to effect reduction of the pres sure in the brake cylinder-to a.;predetermined low pressure and then restore it automatically within a certain normal interval of time. In the event that the Decelostat pilot valve pipe connecting the Decelostat pilot valve and the control valve device is ruptured, orin the-event.

that the Decelostat pilot valve sticks open,- the control valve device is operative automatically to cause destoration of the supply of fluid under pressure to the brake cylinder upon the elapse of an interval of time, thus insuring reapplication of the brakes notwithstanding the rupture of the pilot valve pipe or the sticking open of the Decelostat pilot valve. p

Due to the specific construction of the control valve device in the aforesaid, Patent 2,417,209,

a certain interval of time is required to recharge the control valve device in orderto render it responsiveto a subsequent wheel slip operation.

In the event that two wheel slip operations follow each other in close succession, the control valve device of the aforesaid patent may not be conditioned to respond promptly to effect a reduction of the brake cylinder pressure.

It is an object of our present invention to provide a control valve device having the same functions as the control valve device of the aforesaid patent but so constructed and arranged, in addition, as to respond instantaneouslyito successive and rapidly recurring wheel slip cycles.

In the aforesaid patentthe time interval that elapses before resupply of fluid under pressure to the brake cylinder to effect reapplication of the brakes occurs following rupture of the pilot valve pipe orsticking open of the Decelostat pilot valve is, moreover, not uniform but varies in accordance with the degree of the pressure established in the brake cylinder.

It is another object of our present invention to provide a control valve device which is restored to the condition ,for resupplying fluid under pressure to the brake cylinder upon the elapse of a substantially uniform interval of time following rupture ofthe pilot valve pipe or sticking open of the Decelostat pilot valve, regardless of the degree of pressure established in the brake cylinder at the time rupture of the pilot valve pipe or sticking open of the pilot valve occurs.

The above objects,'and other objects of our invention which will be made apparent hereinafter are attained by an embodiment thereof subsequently to be described and shown in th accompanying drawings, wherein I Fig. 1 is a simplified diagrammatic View of t fluid pressure brake control apparatus including our novel control valve device therein, and

Fig. 2 is an enlarged vertical sectional View, with parts in one plane for clarity, showing the. detailed construction of our novel and improved: control valve device.

'" Description reservoir 3 which is normally charged as by .a

fluid compressor not shown; a control pipe and manually controlled mechanism, typified in simplified form by a brake valve for controlling I spending to the pressure established in the con trol pipe 3. p i i The control valve device 6 comprises a secltionalized casing including a pipe bracket and mounting portion l4 having two substantially parallel faces on opposite sidesthereof, to one of which faces a vent valve portion i5 .is attached as by screws or bolts not shown, with a suitable sealing gasket intervening, and to the other face of which an auxiliary portion 16 is'attached as byscrews or bolts not shown, with a suitable sealing gasket intervening. The vent valve portion has a vcap portion l'l attached'thereto as the supply of fluid under pressure from the reser= w voir 3 to the pipe 4 and the :releaseof 'iiiiid under pressure from the pipe 4. A control valve device 6, constructed according to our invention is interposed between the control pipe 4 and the brake cylinder i, connection being made from the control pipe 4 to the control valve device 6 througna branch pipe 1 of the control .pipe and to the brake cylinder 1 .through a soecalled brake cylinder 'pipe 8, Associated with each of the wheel and axle units is a -SO+CEL11C1 Decelostat? or wheel-slip detector 9, .oflthe rotary inertia type, each Decelostat including a pilot vialve device ill carried on the outer end of the axle journal casing and connected to respective branches of -a pipe, hereinafter called the. pilot. valve pipe H; leading and connected to the control valve device 8. l V I Considering the parts of the equipment in greater detail, the brake Va1ve5 may be of the well-known self=la-pping type, having an operat-I ing' handle l2 secured to the outer end of a rotary operating shaft that is turned by rotation to control supply and-release valve mechanism. In the normal or brake release position of the brake valve handle 1 2, is vented to atmosphere from the control pipe t by way Of the exhaust pOI't and 131136 l3 at the brake valve. Whenthe :brake valve handle I2 is shifted out of'itS brake release position into its application Zone; the exhaust connection ofv the control pipe 4 is closed and asuppiy ci a section is openedbetween the reservoir 3 and the control pipe 81; The nature of'tne brake valve mechanism is such that the-supply or filild under 3 pressure to thecontroi ipe 3 is automatically terminated wh'en a certain ressure is established therein correspondingsabstaiitiauy to the degree of displacement or the brake valve handle 12 out or its brake release-position. Thus the greater the de ree or eisplacementof'the brake valve handle out of brake release position, the

1 greate is the pressure established in the con-'- trol pipe l. -'-I-lie brake valve 5 also'has'apre'sfluid under pressure by screws or'bolts-not shown, with a suitable sealing gasket intervening. v

The pipe bracket portion M is, provided with I three passages l8, l9 and 20 out of which open ports to which the pilot valve pipe I i, the branch pipe 7 of the control pipe, and the brake cylinder pipe 3 are respectively cnnectect E'mbodied in the vent valve portions-l5 is a differential piston valve device 2! comprising an annular piston vl2 operative" in a circular bore 23; and a vclisc type piston valve 24 of smaller diameter, operative'in a bore '25 oil correspondingly' smaller diameter, the two bores being coaxiallyrelatedand the piston 22 and piston valve I 2:? being-connected by atubular stem 2%.. a

A coil spring '21 eXtendstlirough-the stem 26,

"in interposed relation between the inner face of the cap section I! and the inner face of the piston valve i2 2, and 'yieldi'ngly urges the differe'ntial piston valve device'll downwardly to a sure-maintainingfeature in'that should-the pressllr in tnecontrol 151159 tend to reduce from that corresponding to the degree of displacement of sure to be supplied to the control pipe to maintain apressure therein corresponding to the position of the brake valve handle.

Under vnormal conditions, communication between the branch pipe "ll of the control pipe 1 the brake valve handle out of its brake release position, the supply y'alve ofithe brake valve is I I automatically operated tocause fluid under presposition in which the piston valve 24 seats onia seat rib "28 that surrounds a vent port 23.

Formed in surrounding relation to the stem 26 is an annular chamber til that is open to, the inneiiface' of the annular piston 22 and is con"- nectd by ab'ranch" passage 35 :to the passage 19 within the pipe bracket portion .l d.

The chamber -32'=formed within the 'bore '23 at the outer face of the annular piston :22 isalso connected to the passage w through a passage 335a Branch passage taanda choke-fitting 35 vof the screwtypeinterpcseu in a bore connecting the branch passage Mand the passage 9. The bore containin'g'the choke-fitting 35 is open tothe face of the -pipebracket portion M to'enable'installa t'ion-an-d-reinoval of t he cholie fi-tting while the vent-valve portion IE is removed from that face. Also-formed in the vent valve portion lE is an annular chamber 36 that communicateswith the annularchanibertll througha series of circularly arranged peripherally spaced ports'3'l.- The passage 2t inthe pipe bracket :portion it leads to and opens into the chamber 365-. I

The -passage '33 extends-into the auxiliary portion 1 5, and-a branch passage 38 thereof leads to -a bore or passage '39 that opens at the faceof the auxiliaryporti'on lB-ahd registerswith a-corresponding portion of the bore 39 in the pipe bracket portion .14; hose-ted in the bOIe 391159;

screw-type choke-'fitting filll adapte to b63111- stalled and removed through the open end of the bore 39 while the'auXiliary-portion 16 is re-a I moved from-thepipebracket portion it. I

and the brake cylinder-pipe ll-so that aiiuid presbrakes on the car. wheels 2 to a degree corresure is established sill the brake cylinder corre-, I j sponding to the pressureestablished in. the con= The'passage 'lB, -to whichthe pilot valve pipe l'l is'conne'cted, leads toahd opens into the portion of-thebore 39ihlih' auxiliarypo'rtion M. The passage l9, to which the "'branchpi'pe I is connected, also opens into the bore 39 but'the, connection is closed-byrneans of a screw plug 4i installed through the openend-of the bore 39 while the auxiliary portion .16 is removed. "The connection between thepassa e 19 and the bore 39 may be omitted if desired for it has no utility in the control valve device as shown.

It will accordingly be seen that when fluid under pressure is supplied from the control pipe 4 through the pipe I to the passage I9, fluid under pressure is supplied through the orifice of the choke-fitting 35, branch passage 34, passage 33, branch passage 38 and the orifice of the chokefitting 40 to the passage is and the connected pilot Valve pipe H.

Embodied in the auxiliary portion I6 is a valve 42 of the poppet type adapted to control a connection between the passage 33 and the pilot valve pipe H in a manner to enable rapid charging thereof in by-passing relation to the chokefitting 40. To this end, the poppet valve 42 is guided by means of a fluted stem in a bore connecting a first chamber 43, into which the passage 33 opens, and a second chamber 44 out of which a passage 45 leads that is connected into the bore 39 outside the choke-fitting 49.

A coil spring 45a, interposed between a suitable perforated collar 46 and the valve 42, yieldingly biases the valve to seated position.

Associated with the valve 42 is a flexible diaphragm 41 having a chamber 48 at one side thereof to which fluid under pressure is supplied, in the manner presently to be described, for exerting a force upwardly on the diaphragm and through a suitable follower 49 to effect unseating of the valve 42. The follower 49 has a cup-shaped annular flange 50 guided in a suitable bore and a central stem portion which extends slidably through a circular bore connecting the chamber 44 to a chamber 52 at the upper side of the diaphragm 41 which is maintained at atmospheric pressure through a vent port 58. A suitable sealing or grommet ring 53 of rubber or rubber composition, oontained in an annular groove on the stem of the follower 49, provides a suitable seal to prevent leakage of fiuid under pressure from the chamber 44 along the stem of the follower to the atmospheric chamber 52.

Surrounding the stem of the follower 49 is a cup-shaped washer 53a conveniently retained on the stem of the follower when the follower is removed from the casing or auxiliary portion l6, as by a snap ring 54. Interposed between one side of the washer 53a, which seats against a suitable surface of the casing, and the follower 49 is a coil spring 55 that yieldingly urges the follower and diaphragm 41 downwardly to a position in which the central part of the diaphragm engages a. boss or stop 56 formed on a cover plate 51; Cover plate 51 is secured to the portion 16 by screws or bolts not shown and clamps the diaphragm 41 in position.

The strength of the'springs 45a and 55 is such that whenever the pressure of the fluid in chamber 48 exceeds a value of approximately five pounds per square inch, the follower 49 is shifted upwardly to engage the end of the fluted stem of the valve 42 and effect unseating of the valve 42. With the valve 42 unseated, the pilot valve pipe H and the chamber 32 of the vent valve portion are in constant communication in bypassing relation to the choke-fitting 40 by way of the passage l8, bore 39, passage 45, past the unseated valve 42 and passage 33.

The chamber 48 at one side of the diaphragm 41 is connected to a so-called timing volume 59, formed in the pipe bracket portion l4, by a passage 60, a branch passage 6!, and a passage 62.

that leads into the volume 59.

- Whenever fluid under pressure is supplied to charge the pilot valve pipe I I, fluid under pressure; is concurrently supplied to charge the chambers 48 and 59by way of a branch passage 63 of the passage 45, past a one-way or check valve 64 of the disc type, to a chamber 65 to which the passage 62 is connected. The check valve '64 is yieldingly biased to a seated position by a coil spring 66 of such a strength'as to load the check valve to a value of about four or five pounds per square inch. i

The timing volume 59 is connected to the passage l8 through a suitable bore containing a choke-fitting 61. Choke-fitting 61 may beof the screw type and isadapted to be installed and removed, as through a port 68 in the outer wall of portion 14 and aligned with the bore that receives the choke-fitting while the auxiliary portion I6 is removed. Port 68 preferably registers with passage 62 in the auxiliary portion l6 as: shown to provide a connection between passage 62 and volume 59.

Due to the fact that the check valve 64 unseats at a relatively low pressure of four or five pounds per square inch, the timing volume 59 and the chamber 48 are charged at a rapid rate upon the supply of fluid under pressure from the branch pipe I of the control pip'e into the passage l9 rather than at the relatively restricted rate through the orifice of the choke-fitting 61.

There is also provided in the auxiliary portion" l6 another one-way or check valve 69 of the disc. type, similar tothe check valve 64. The check valve 69 is loaded by a coil spring 10 having such strength as to require twenty-five pounds per square inch fluid pressure to effect unseating of the valve. The check valve 69 is adapted to seat on an annular seat rib surrounding a port opening out of the passage 60. A chamber II at the outer face of the check valve 69 is connected by a passage 12 to the passage 63.

It will be apparent, therefore, that assuming the timing volume 59, the pilot valve pipe I l and passage 18 to be charged to the same pressure,

a twenty-five pound reduction of the pressure in the pilot valve pipe with respect to the pressure in the volume 59 will cause unseating of the check valve 69 to effect a reduction of the pressure in the timing volume 59 and the connected chamber 48 at a rapid rate in accordance with the rapid rate of reduction in the pilot valve pipe ll until the pressure in the timing volume 59 and chamber 48 reduces to below a pressure of twenty-five pounds per square inch. When the pressure in the timing volume 59 and the connected chamber 48 reduces to below twenty-five pounds per square inch, the loading spring 19 will seat the check va1ve69 to prevent the further escape of fluid.

under pressure past the check valve 69 from the chambers 48 and 59. With check valve 69 seated, fluid under pressure escapes from the chambers 48 and 59 only through the orifice of the chokefltting 61. The timing arrangement thus provided is such that the restricted flow of fluid under pressure through the orifice of the chokefitting 61 is effected or initiated in every instance from a uniform pressure of twenty-five pounds per square inch in the timing volume 59.

Also embodied in the auxiliary portionv I6 is a disc valve 13, hereinafter referred to as the cutoff valve. The cut-off valve 13 is under the control of a diaphragm 14 which is secured in position by a cover plate 15 suitably attached to the auxiliary portion l6. Interposed between the diaphragm 14 and the valve 13 in a chamber 16 is a coil spring H of relatively light strength for,

spring 80 is eifective to exert tached to the outer face of the diaphragm J4,

and the cover plate 75 is arelatively heavycoil spring 80 which is effective, through the diaphragm M, to exert a force to seat "the'cutol'i Meats;

valve 13. The chamber 8| at the outside ofthe diaphragm tit is constantly through a port 82. I 1

The spring as is so'designed 'that a-fiuid ;pres-' sure of the order of twenty-five poundsper square open to atmosphere inch in the chamber W; at the lower side of the i iaphragm is effective to overcome the force of the spring and shift the diaphragm upwardly to relieve the cut-off valve '13 of .the force of the spring 8H resisting unseating of the cut-off valve. Conversely, when the pressure of the fluidin-the chamber 76 beneaththe diaphragm 14 reduces to below twenty-five pounds per square inch the I a force to maintain the cut-off valve'l3 seated. l

The cut-ofi valve 73 is effective when unseated upwardly to permit theilow of fluid underpressure therepast from the chamber 43 to the chamber I8 to which the passage is connected. :It will be seen, therefore, that since the pressure in the chamber 76 corresponds to the pressurein the brake cylinder by reason of the connection established through the passage 20, fluid under pressure will be vented from the chamber 32 of the vent valve portion 15 by wayof the passage 33, chamber '43, past the cut-off valve 13; chamber 76, passage 2!], annular chamber 35, ports 37 and exhaust port 29 of the vent valve portion "[5 whenever the differential piston valve device :21 of the vent valve portion is actuated upwardlyto its operated position inithe' manner presently to bedescribed. It will also be apparent that when the pressure in the brake cylinder-reduces to :a'

value below twenty-five pounds per square inch, the spring 80 becomes effective to seat the cut-oil valve 13 to prevent the .venting'of the chamber 32 of the vent valve portion past thecu't-ofi valve and through the exhaust port 29 of the vent valve portiorn i 1 The fDecelostats or .wheel-slip detectors 9 may be of the rotary inertia type disclosed in the copending application, Serial No. 533,284 of Joseph-C. McCune. and George K. Newell, .file'd April 29, 1944, now Patent No. 2,447,710, granted August 24, 1948, and assigned to'the assigneeof the present application. Since reference maybe had'to this copending application for d'etailsof the Decelostat, it is deemed unnecessary to further describe these devices other than topoint out that they comprise. essentially a fly-wheel element which is operative in response'to acceleration or deceleration of the wheel and axle units at a rate exceeding a certain ratefsuch as ten-- miles per hour per second, which-occurs only when the associated wheel 2 slips,t'o efieot unseating of the pilot valve devices I 3 The term slip as used herein refers to the rotation of a vehicle wheel at a speed different {from that corresponding to vehicle or rail speed at a given instant and may be induced either' by excessive propulsion torque or excessive braking torque exerted on the Wheel. When excessive braking torquev is exerted on ia 'wheel, it der celerates at an abnornfally rapid rate in excess of ten miles per hour per second, which rate of clecelerationtis never attained unless the. wheels are actually slipping.

The term slide as employed herein inscone nection with vehicle wheels refers to a non-ra tative or locked condition of the wheels as distinct from a slip".condition in which the Wheels are rotating. It will be understood, therefore,

that whenever a vehicle wheel 2 begins toslip,

the corresponding pilot valve device Hi .is"un-- seated to efiect a rapid venting to atmosphere: anda consequent reduction of the pressure ,inthe pilot valve pipe H and the connected chamber 32 of the ventvalve portion of thecontrol valvedevice 8. This initiates a sequence of operationwhich will be presently explained.

U Operation In order to further explain "the operation{of the control valve'device B, let it be assumedl hat the operator desires to initiatea brake applica: tion while the vehicle having the equipment shown in Figure 1 is traveling under power. After first shutting ofi propulsion power, the ou-:- erator. shifts the brake valve handle 12 outofjit-s" brake .releaseposition a desired amount into the brake application zone. to cause a fluid pressure.

to be established in the control pipe l 1091x813 spondingto the desired degree of brake application. -With the control-pipe d charged .-'-with. fluid under pressure, fluid under-'pressureflows through the branch pipe I, passage i931 branch passage 3!, annular chamber til, ports'35,;annu'-* lar chamber 36, passage .126, and pipe '8 tothe.

brake cylinder l, the pressure established inuthe brakecylinder corresponding to that established in the control pipe 4.

The piston valvedevice 2i remains seated the position in which it is-shown in EFigure '2' while fluid under pressure.isbeing-supplied toithe brake cylinder as just described, by .reasonlof the sufficiently rapid flow of fluid under pressure: through the orifice of the choke fitting 35*to chamber. 32 above the piston valve deviceiiLthe build up of the pressure in the chamber i32rbei'ng' sufiiciently rapid :to prevent the developmentor a. differential fluid pressure .force on the :piston valve device 25 sufficient toovercome thedoWnwardlyexerted force of the spring 21. a

The chamber 16 in'the auxiliary .DOItlOHIOf" the control valve mechanism ills concurrently charged with fluid at the pressure established in the brake cylinder. by flow. of fluid. under pres-- sure through the passage .26 to the chamber 16,-

the .force of the spring '86 acting to hold the cut-0E valve '13 seated being removedwhen the brake cylinder pressure .exceeds twenty-five pounds per square inch.

.Fluidunder pressure supplied to the passage" l9 also-flows through the'orifice of the choke fitting 135, branch passage a passage 33, branch passage 38, the orifice .of-the choke-fitting 4.3;

bore 39 andpassage l8 to' the pilot valve pipe H,-

thereby charging thepilot valve pipeto the pres-l svre-establishcd'in thebrake cylinder. concur rently with the charging of--thepilot valve pipe," fluid under pressure flows from thebore 39" by way of the passage fi, branch-passage 63; past" the check valve 64, through the passage fif-to charge the timing volume-=59 at arapidrate. the same time, the chamber 43 beneath the dialphlegm-'41 is charged to the'pressu're established in the timing volume 59 through the branch passage GI and the passage 60.

When the pressure established in the timing volume 59 and the chamber 48 exceeds a relatively low value such as four or five pounds per square inch, the upwardly exerted force on the diaphragm 4'1 is transmitted through the stem of the follower 49 to unseat the poppet valve 42. Thereafter, fluid under pressure is supplied to charge the pilot valve pipe, the timing volume 59, and the chamber 48, in by-passing relation to the choke-fitting 40, by flow from the passage 33 past the unseated valve 42, chamber 44, passage 45, bore 39, and passage I8 to the pilot valve pipe II.

It will thus be apparent that rapid charging of the pilot valve pipe, timing volume 59 and the chamber 48 is effected at the time that fluid under pressure is supplied to the brake cylinder I.

So long as the wheels 2 do not begin to slip due to the brake application, no further operation of the control valve device 6 occurs. Moreover, pressure in the brake cylinder may be varied, up or down, in correspondence with variations in the pressure in the control pipe 4 to either increase or decrease the degree of brake application on the wheels 2'.

Should one of the wheels 2 begin to slip at the time a brake application is initiated or during a brake application, automatic operation of the control valve device 6 is effected in the manner which will now be described, The unseating of the pilot valve device I9 of the *Decelostat '9 associated with the slipping wheel unit efiects a rapid venting of the fluid pressure in chamber 32 above the piston valve device 2| of the vent valve portion I by way of the passage 33, past the unseated valve 42, passage 45, bore 39, passage I8, and pilot valve pipe I I. Due to the restriction of the orifice in the choke-fitting 35, the pressure in the annular chamber 30 beneath the piston 22 cannot reduce as rapidly through the choke-fitting to the passage 33 as the pressure in the chamber 32. Accordingly, sufllcient differential fluid pressure is promptly built-up on the piston valve device 2I to overcome the downward force of spring 2'! and to cause shifting of the piston valve device 2| upwardly into contact with the inner face of the cap portion H.

In its operated position above the ports 3! to which it is moved as just described, the piston valve 24 closes oif the connection between the passage i9 and the passage 29. At the same time, with the piston valve 24 above the ports 31, the passage 20 and the brake cylinder I are connected to atmosphere through the exhaust port 29 of the vent valve portion I5, reduction of the pressure in the brake cylinder being thus effected at a rapid rate.

Once the piston valve device 2I is operated to its upper position to vent fluid under pressure from the brake cylinder, fluid under pressure is automatically vented from the chamber 32 of the vent valve portion I5 at a rapid rate by way of the passage 33, past the cut-off valve I3 which unseats against the relatively light resisting force of spring 'II, passage 29, annular chamber 36, ports 3?, and exhaust port 29. It will be seen, therefore, that the unseating of the Decelostatf pilot valve devices I!) merely initiates the operation of the piston valve device 2| to its operative position, the piston valve device 2| being maintained in its operative position thereafter independently of further venting of fluid underv pressure from the pilot valve pipe II by the Decelo l0 stat pilot valve II), by reason of the self-ventingoperation of the piston valve device 2| through the exhaust port 29.

The reduction of the pressure in the timing volume 59 and the chamber 48 lags behind the reduction of the pressure in the pilot valve pipe I I by reason of the restricted orifice in the chokefitting 61. At the same time, however, the pressure in the chamber II at one side of check valve 69 reduces at a rapid rate by reason of the unrestricted communication with the pilot valve pipe passage I8 through passages 12, 63, 45 and bore 39. A sufiicient-differential fluid pressure force is thus promptly built-up to effect the unseating of the check valve 69 upwardly and the consequent reduction of fluid under pressure in the timing volume 59 and the connected chamber 48 at a rapidrate concurrently with the reduction of the pressure in the pilot valve pipe II and the chamber 32 of the vent valve portion I5 by flow past the unseated valve 42, past the cut-off valve I3, through the passage 20 to atmosphere through the exhaust port 29of the vent valve portion I5. Such rapid reduction of the fluid pressure in volume 59 and chamber 48 continues until such time as the pressure in the volume 59 and chamber 48 reduces to below twenty-five pounds per square inch. When the .pressure in the volume 59 and the chamber 48 reduces to below twenty-five pounds per square inch, check valve 69 will be seated by the force of the loading spring I0 and no further reduction of pressure in these chambers will occur past the check valve 69 but will occur solely by reason of flow through the restricted orifice of the choke-fitting 61. A pneumatic timing operation is accordingly initiated uniformly following the instant that the pressure in the timing volume 59 reduces to a pressure of twenty-five pounds per square inch. Thus a uniform timing interval, substantially unaffected by the degree of brake cylinder pressure established, is provided fora purpose hereinafter to be explained.

Due to the rapid and prompt reduction of the pressure in the brake cylinder following upon the occurrence of the slipping condition of the wheel unit, the slipping wheel unit promptly ceases to clecelerate and begins to accelerate back toward a speed corresponding to vehicle or rail speed. The Decelostat pilot valve I0 associated with the slipping wheel unit is restored to closed position terminating further venting thereby of the pilot valve pipe II when the rate at which the slippingwheel unit accelerates back toward vehicle speed reduces below a value of approximately ten miles per hour per second. Ordinarily, the pilot valve device III will be reclosed while the reduction of the pressure in'the chamber 32 of the vent valve portion I5 is still continuing by 'valve device Ill reseated, therefore, the reseating of thecut-off valve I3 will effect termination of the further venting of fluid under pressure from the chamber 32 of the vent valve portion I5. Consequently, due to the prompt build-up of pressure in the chamber 32th1jough the orifice of the choke 11? fitting 35 the fluid pressure differential active to maintain the piston valve device 2! in its upper or operated position is sufficiently and promptly reduced so as tov enable the spring 21 to promptly restorethe piston valve device 21 downwardly to its seated position in which it is shown in Figure 2. Actually, due to the: slight operational lag of the piston valve device 2|, the pressure in the brake cylinder may reduce to as'low as five pounds per square inch before therestoration of piston valve device 2| to its normal position and the consequent termination of. further venting of to a brake application; the piston valve device 21 of the vent valve portion 15 will have been re'-- in the control pipe 4. Moreover, since there is no fluid under pressure from the brake cylinder ocapplication of the brakes to a degree corresponding to the pressure established in the control pipe 4 v At the same time that fluid under pressure is resupplied to the brake cylinder, the timing volume 59 and the connected chamber 48 are again rapidly recharged, in the manner previously described, by flow of fluid under pressure past the check valve 64. It should be understood, that by reason. of the fact that the reduction of the pressure in the timing volume 59 lags behind the reduction of the pressure in the brake cylinder, the piston valve device 2! of the vent valve portion I 5 will have be'en'restored to its normal position, in the manner just described, before the pressure in the timing volume 59 and connected chamber 48 reduces to a low value of four or five pounds per square inch. Suflilcient pressure therefore remains in the timing volume 59 and in the connected chamber 48 under normal conditions to maintain the valve 42 unseated. Consequently, upon the resupply of fiuid' under pressure to the brake cylinder, recharging-of the timing volume 59 and chamber 48 is rapidly effected by flow of fiuid under pressurefrom the passage 33 past the valve 42 and by way of the chamber 44 passage 45,-branch passage 63, and thence past the check valve 54. Thus, there is no delay in the recharging of the timing volume 59 and the chamber 48. At the same time due to the fact that the valve 42 remains unseated, the piston valve device 21 of the vent valve portion I5 may be instantly responsive to a possible subsequent operation of the pilot valve device of a Decelostat'!-! resulting from an immediately recurring slippin condition of the wheelfollowing upon reapplication of'the brakes.

Should the same wheel unit which previously slipped, or another wheel unit of the same truck, begin to slip substantially at the time that reapplication ofwthe brakes is being efiecte'd, the piston valve device 2| of'the vent valve portion l5 will immediately respond to the unseating of the pilot valve device It to again effect reduction of the pressure in the brake cylinder I followed by the automatic restoration of the pi'ston valve device 2| to resupply fluid under pressure to the brake cylinder in the manner previously described.

It will thus be seen that our improved control valve device 6 is specifically constructed and operative to respond instantaneously to rapidly repeated and recurring wheel slip cycles, a characteristic not" presenter existent in previou-scon trol valve devicesof this type. I

When the vehicle comes to a stop'in response danger'of wheel slip occurring-while the vehicle is stopped, the degree of brake application may be increased to any desired degree required to hold the vehicle on a grade. 7

When the operatoragain desires to proceed, he may release the brakes merely by restoring the brake valve handle 12 to it brake release position, thus reducing the pressure in the control pipe 4 and, correspondingly, that in the brake-cylinder l to atmospheric pressure.

Thus far a normal operation of the pilot valve device it and continuity or integrity of the pilot valve pipe H has been assumed. In the event, however, that a pilot valve device ill operates improperly and sticksin open position once it is operated, or in the event that the pilot valve pipe I I is accidentally ruptured or broken, our control valve device is operative automatically to insure reapplication of the brakes.

If, therefore, the pilot valve device Ill sticks in open position so as to continue the venting of fluid under pressure from the pilot valve pipe I I, the following operation occurs. Let it be assumed that the controlvalve device 6 is operated in the manner previously described to effect the reduction of the. pressure in the brake cylinder following upon the initial operation of the Decelostat pilot valve device l0 and that the pressure in the brake cylinder has reduced to below twenty-five pounds per square inch to effect reseating-of the cut-01f valve 73; With the pilot valve device Ill stuck open and continuing to vent ,the pilot valve pipe H, the, differential piston valve device 2! ofthe vent valve portion [5 will not be instantaneously restored to its normal position uponreseating of the cut-off valve 73, by reason of the continuing reduction of the pressure in the chamber 32by flow from the passage 33 past the unseated valve 42, passage ;bore 39, passage I8 and pilot valve pipe I I. However, after a predetermined uniform interval of time, approximately three'seconds, following the reduction of the pressure in the timing'volume '59 to twentyfivepounds per square inch, the pressure inthe timing volume and the connectedchamber 48 will have reduced through the orifice ofthechokefitting 6: 1 to a'value below four or five pounds per square inch; In such case, therefore, the spring 55 becomeseffective to shift the diaphragm 411 and the iollower49 downwardly, thereby causbuild-up of the pressure in the chamber 32 through the orifice of the choke-fitting 35.

' It will be seen,- therefore, that if the difierential piston valve device 2| is not-operated to its normal position restoring the supply communication tothe brake cylinder in' its normal man ner, it'will be. restored thereto at all events by reason of the pneumatic timing arrangement pro-.

13 vided in our control valve device 6. It will be observed that the timing interval is substantially uniform regardless of the pressure established in the brake cylinder, a characteristic not present in previously known control valve devices of this type.

With the Decelostat pilot valve device it! stuck in open position, it will be seen that the brakes may be applied and released in normal manner once the differential piston valve device 2! has been restored to its normal position in response to the pneumatic timing operation. However, due to the fact that charging of the pilot valve pipe H and of the timing volume 59 and its connected chamber 48 cannot be efiected so long as the pilot valve is vented by the Decelostat pilot valve stuck in open position, it will be understood that the valve 42 will remain in its seated position due to the fact that a pressure in excess of four or five pounds per square inch cannot be built-up in the chamber 43 sufficient'to unseat the valve 42. Thus it will be apparent that while the brakes may be applied and released in normal manner under the control of the o'perator, the anti-wheel sliding protection feature of the control valve mechanism will be lost so long as the Decelostat pilot valve device I8 'is stuck in open position. It will also be apparent that during a brake application, fluid under pressure will flow at a restricted rate through choke fitting 40 to the pilot valve pipe H causing a continuous blow at the pilot valve l8 that is stuck open. The amount of fiuid under pressure escaping through choke 40 is however limited and may be tolerated in an emergency.

A situation similar to that which occurs when a Decelostat pilot valve device I sticks in open position occurs when the pilot valve pipe I l itself is ruptured or broken, for some accidental reason, as by striking an object along the right of way. Obviously, if the pilot valve pipe H is broken while the brakes are released, application and release of the brakes under the control of the operator may be effected in the same manner as if the Decelostat pilot valve device [0 were stuck in open position, the anti-wheel sliding protective feature of the control valve device 6 being lost. In the event that the pilot valve pipe H be comes ruptured while a brake application is in effect on the vehicle, it will be seen that the differential piston valve device 2! will be operated to effect a reduction of brake cylinder pressure in the same manner as if the Decelostat pilot valve device I!) had initiated the operation normal manner in response to the occurrence ofa wheel slip condition.

By reason of the pneumatic timing arrangement, the differential piston valve device 2! will be restored to its normal position eifecting reapplication of the brakes at all events at the expiration of a certain uniform interval of time following the reduction of the pressure in the timing volume 59 to twenty-five pounds per square inch. Application and release of the brakes may, there-' fore, be effected in normal fashion under the control of the operator, except that the anti- Wheel sliding protective feature of the control valve mechanism will be lost, just as in the case of the Decelostat pilot valve being stuck in open position.

In view of the fact that the safety of the vehicle and its passengers is of paramount consideration, the fact that anti-wheel sliding protection, normally provided by the control-valve de- I4! vice are lost upon the rupture of the pilot valve pipe or the abnormal operation of the pilot valve device I0 is of secondary consideration.

Having now described our invention, what we claim as new and desire to secure by Letters Patent, is:

l. The combination of a fluid pressure controlled valve device having a normal position in which'it establishes a communication through which fluid under pressure may be supplied to a fluid pressure receiving device and operative in response to a rapid reduction of the pressure in a control chamber to a different position in which the said communication is cut oii and an exhaust communication is established through which fluid under pressure, is released from the receiving device, a passageway through which fluid under pressure may be vented from the control chamber under" the control of said valve device while in itsisaid different position thereby to cause a continued reduction of the pressure in the control chamber to maintain the said valve device in its said different position, and valve means operatively controlled by the pressure of the fluid in the receiving device in such manner as to open said passageway so long as the pressure in said receiving device exceeds a certain value, and to close said passageway'upon the reduction of the pressure in said receiving device to below said certain value to render said value device ineffective in its said difierent position to continue the reduction of the pressure in the control cham. ber, thereby to enable restoration of the valve device to its normal position,

2. The combination of a fluid pressure controlled valve device having a normal position in which it establishes a communication through which fluid under pressure may be supplied to a fluid pressure receiving device and operative in response to a rapid reduction of the pressure in a control chamber to a different position in which the said communication is cut off and an exhaust communication is established through which fluid under pressure is released from the'receiving device, a one-way valve device subject in opposing relation to the pressure in the chamber and the pressure in the receiving device and adapted to be unseated in response to a reduction of the pressure in the receiving device to cause a corresponding reduction of the pressure in the control chamber simultaneously with the reduction of the pressure in the receiving device thereby to maintain the said valve device in its said different position, and fluid pressure controlled means subject to the pressure in the receiving device and effective so long as the pressure in the receiving device exceeds a certain value to permit unseating of said one-way valve device and efiective in response to'a reduction of the pressure in the receiving device to below said certain value for preventing the unseating of said one- Way valve device and thus the further reduction of thepressure'in the control chamber under the control of the valve device, and means effective to cause charging of the control chamber of the said valve device and the consequent restoration of the valve device to its normal position when unseating oi the one-way valve device is prevented by said fluid pressure controlled means.

3-. The combination of a fluid pressure con trolled valve device having a normal position in which it establishes a communication through which fluid iunder pressure may be supplied to a fiuid'pressure receiving device and operative in response to a rapid reduction of the pressure in accuse a controlchamber to-adifferent: position inwhich the-said communication is cut oiiand anexhaust communication is established through which fluid under pressure is released from the-receiving device, a one-way valve device subject in opposing relation to the pressure in the chamber and the pressure in the receiving device and adapted to be unseated in response to a reduction: of the pressure in the receiving device to cause a corresponding reduction of the pressure in the control chamber simultaneously with the reduction of the pressure in the receiving device thereby to maintain the said valve device in its saidzdifierent position, resilient means adapted to exert a force suflicent to prevent unseating of said one-way valve, fluid pressure responsive means subject to the pressure in the receiving device in a manner such that it renders said resilient means ineffective to prevent unseating of the said one-way valve device so long .as the pressure in the receiving device exceeds a certain value and renders said resilient means efiective to prevent unseating of said one-way valve device whenever the pressure in said receivingv device reduces below said certain value, and means effective when said one-way valve device is reseated by said resilient means as a consequence of the reduction of the pressure in the'receiving device, for so recharging the control chamber as to effect restoration of the valve device to its normal position. i

4. The combination of a fluid pressure controlled valve device, having a normal positionvin which it establishes a communication through which fluid under pressure may be supplied to a fluid pressure receiving device and operative in response to a rapid reduction of the pressurein a control chamber associated with said valve device and chargeable with fluid under pressure concurrently with the supply of fluid under pressure to the fluid pressure receiving device, said valve device being operative in response to a rapid reduction of the pressure in the control chamber to a different position in which the said supply communication is cut off and an exhaust communication is established through which fluid under pressure is released from the receiving device, a piloting communication, a chamber, means providing a restricted communication through which said piloting communication and said chamber are'chargeable at a restricted rate concurrently with the supply of fluid under pressure to the receiving device, fluid pressure responsive valve means subject to the pressure of the'fluid established in said chamber and 0perative to establish an unrestricted communication' from said control chamber tosaid piloting communication and said chamber in responseto a pressure in said chamber exceeding a certain low value whereby to cause rapid charging ,of said plioting communication and said chamber concurrently with the charging of said control chamber and reduction of thepressure in said control chamber at a rapid rate upon venting of said piloting communication.

5. The combination of a fluid pressure controlled valve device having a normal position in which it establishes a communication through which fluid under pressure may be: supplied :to a fluid pressure receiving device, a control chamber associated with said valve device and chargeable with fluid under pressure concurrently with the supply of fluid under pressure to the fluid pressure receiving device, said valve. device being operative in response to arapid reductioniof the;

leased from the receiving device, a piloting com munication chargeable concurrently with said control chamber and adapted to have the pressure therein reduced at a rapid rate, a chamber chargeable concurrently with said pilotingi communication, fluid pressure operated valve means responsive to a pressure in said chamber exceeding a. certain value for-establishing an unrestricted communication between' said control chamber and'said piloting communication whereby said piloting communication is charged at a rapid rate" and whereby reduction ofv the pressurein the piloting'communication: at a rapid rate'results in reduction of the pressure in the control chamber at a corresponding rate, said Valve'means beingeflective to cut off said unrestricted communication upon the reduction of the pressure in the said chamber below said certain value to cause restoration of the valve de-; viceto its normal position, and means for effect.- ing reduction of thepressure in said chamber inre'sponse to a reduction of, the pressure in said piloting communication.

6; The combination of a fluidpressure controlled valve device having a normal position in which it establishes 'a communication through which fluid under pressure may be supplied to a fluid pressure receiving device, a control chamber associated with said valve device andchargeable with fluid under pressure concurrently with the supply of fluid under pressure to the fluid operative in response to a rapid reduction of the pressure in said control chamber to a different. position in which it cuts ofi said supply communication and establishes an exhaust communication through which fluid under pressure is released irom the receiving device, a piloting communication, means providing an unrestricted communication between said piloting communication and said control chamber whereby said piloting communication may be charged at a rate corresponding to the rate of charging ofsaid control chamber and whereby upon a rapid reduction of the-pressure in said piloting communication a correspondingly rapid rate of reduction of the. pressure in said control chamber is effected, a timing chamber, a first checkivalve device interposed between the piloting communication'and the timing chamber adapted to per.- mit' rapid charging of said timing chamber in correspondence with the charging of said piloting communication, a second check valve device interposed between said timing chamberandsaid piloting communication adapted to permit the flow of fluid under pressure therepast from the. timing chamber to the piloting communication upon a reduction of the pressure in the'piloting, communication only so long as the pressure in V the-timing chamber exceeds a certain uniform pressure, means effective at all times to cause reduction ofthe pressure in the-timing chamber at a restricted rate concurrently with the reduction of the pressure in the piloting communi-,-,

cation at a rapid-rate, and fluid pressure operated valve means responsive to a reduction of the pressure in the timing chamber to below a: certain low value for closing the unrestricted communication between said piloting communication and said control chamber whereby to. enable the recharging of the control chamber and the con- 17 sequent restoration of the said valve device to its normal position upon the expiration of a certain uniform time following the reduction of the pressure in the timing chamber to below said certain uniform pressure.

'7. The combination of a fluid pressure controlled valve device having a normal position in which it establishes a communication through which fluid under pressure may be supplied to a fluid pressure receiving device, a control chamber associated with said valve device and chargeable with fluid under pressure concurrently with the supply of fluid under pressure to the fluid pressure receiving device, said valve device being operative in response to a reduction of the pressure in the control chamber at a rapid rate .to a different position in which the said supply communication is cut off and an exhaust communication is established through which fluid under pressure is released from the receiving device, a piloting pressure in the control chamber and whereby reduction of the pressure in the control chamber at a rapid rate is efiected in response to the rapid reduction of the pressure in the piloting communication, a cut-oil valve device adapted to permit fluid under pressure to be'vented therepast from the control chamber while the said valve device is in its said difierent position thereby to continue the reduction of the pressure in the control chamber and maintain the valve device in its said difierent position so long as the pressure in the fluid pressure receiving device exceeds a certain value, said cut-off valve device being effective to prevent the reduction of fluid under pressure in the control chamber under the control of the valve device when the pressure of fluid in the said receiving device reduces to below said certain value thereby to cause charging of the control chamber and the consequent restoration of the valve device to its said normal position if the reduction of the pressure in the pilotin communication is previously terminated, valve means for closing the unrestricted communication between the piloting communication and the control chamber to prevent reduction of the pressure in the control chamber notwithstanding the continued reduction of the pressure in the piloting communication, a timing chamber, means for causing charging of said timing chamber concurrently with the charging of said piloting communication, means for effecting a reduction of the pressure in the timing chamber at a relatively rapid rate so long as the pressure in the timing chamber exceeds a certain uniform value and thereafter efiective to cause reduction of the pressure in the timing chamber at a relatively restricted rate, and means responsive to the reduction of the pressure in the timing chamber to a certain low value for effecting operation of the said Valve means to close the unrestricted communication between the piloting communication and the control chamber thereby to cause charging of the control chamber and the consequent restoration of the valve device to its normal position in the event that reduction of the pressure in the piloting communication continues after said cut-off valve device becomes effective to prevent further reduction of the pressure in the control chamber under the control of the valve device.

GLENN T. McCLURE. JOHN W. RUSH.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,417,209 McCune Mar. 11, 1947 2,417,211 Newell V V Mar. 11, 1947 

